At wit's end....(can't find dhcp leases)

Bruce Hudson Bruce.Hudson at Dal.Ca
Fri Sep 14 12:20:20 UTC 2007

> My problem is this, and it's driving me crazy. Occasionally, we have
> reason to go back and identify the mac address of a particular ip
> address at a specific time. The obvious place to find this information
> is in the leases file. However, it seems more and more often, we're
> unable to find a lease for a particular ip address at the given time.
> So, my question is twofold -- is anyone else seeing this particular
> issue? And if so, are there any ideas why we might be seeing it? I
> have some theories, but can't find anything on the internet to support
> them.

    The lease file only holds the information the server needs to do its
job consistently across program restarts. It records active leases and it
remembers the last IP address given to each identifier so that the server
can give clients a consistent address if possible but this information is
lost as soon as somebody else is given that address.

    In addition, because the lease file is a text file with an "append
and periodic rewrite", it does contain short-term historical information
until its rewritten. 

    We, as I suspect most people do, scrape historical information out
of the log files and store it.
Bruce A. Hudson				| Bruce.Hudson at Dal.CA
UCIS, Networks and Systems		|
Dalhousie University			|
Halifax, Nova Scotia, Canada		| (902) 494-3405

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